Slag outflow openings for furnaces



Dec. 22, 1942. J. ERMAK SLAG OUTFLOW OPENINGS FOR FURNACES Filed Feb. 4, 1941 FIG/0 FIG.1

INVENTOR= I JO5EF CERMAK .BYQ/QAZM fig.

A T T OR NE Y III Patented Dec. 22, 1942 reat oetic :SLAG OUTFLOW OPENINGS FOR FURNACES Josef Cermak, Hradec Kralove, Bohemia; vested in the Alien Property Custodian Application February 4, 1941, Serial No. 377,340 In Bohemia and Moravia February 22, 1939* Claims. (01. 122-235) This invention relates to furnaces, more particularly to furnaces of steam generators for pulverized fuels, from which the slag is withdrawn in liquid state.

The object of my invention is to provide an opening for outflow of the liquid slag from the furnace which will ascertain a continuous and unobstructed outflow of the slag both at high and low loads of the steam generator.

The invention is further on fully described with reference to the accompanying drawing in which: Fig. 1 is a sectional elevation of the lower part of the slag tap furnace of a steam generator, having an outflow opening, forming the subject of this invention, arranged in its floor; Fig. 2 is a top view and Fig. 3 a transversal section of the opening; Fig. 4 shows a diagrammatic view of a modified form of the opening.

Referring to the drawing, Fig. 1 shows a combustion chamber formed of tube walls and having an oval opening 2 for the outflow of the liquid slag provided in its floor l. The floor I of the chamber may also be constructed of cooling tubes covered with a refractory layer, or it may be formed of heat resisting bricks. The outflow opening 2 has an oval shape, as shown in Fig. 2, and at its upper edge 9, on the greater part of its circumference, it is provided with a dam or similar construction which restricts the outflow of the slag to two points 1, 8. This dam is formed by two water tubes 3, 4 which are suitably bent and cooled either by the water drawn from the boiler circulation similarly as the other cooling tubes of the floor or by the cooling water from another source.

At the two points where the outflow of the slag takes place and which coincide with the points where the two tubes 3, 4 meet each other, there are formed nozzles 5 and 6 to assist the outflow of the slag. These nozzles are also formed by suitable bending of the tubes 3, 4.

The tubes 3, 4 may be provided with studs or fins ll, l4 welded thereto and disposed so as to increase the height of the dam and to give the required shape to the nozzles 5, 6. By using studded or finned tubes 3, 4 it is also rendered possible to use tubes of substantially smaller diameter than the wall tubes, which can more easily be bent and adapted to the shape of the dam and of the nozzles.

The dam as well as the nozzles formed by the tubes 3, 4 and their studs are protected by a layer of plastic refractory material l0 (chrome ore) such as is usually used for protection of tube walls exposed to radiant heat and to the action of the molten slag. This protective layer may give the final proper shape to the dam and to the nozzles as shown in Fig. 3.

In operation, the pulverized fuel is burned in the combustion chamber and, due to the intense radiant heat the produced slag is deposited in liquid state on the walls and on the floor of the furnace. Under normal operating conditions slag flows out continuously through the nozzles 5, 6 of the outflow opening 2 in two streams I, 8, having a circular cross section. When the furnace is operated on low load, the quantity of slag is smaller and its temperature lower, but with respect to the fact, that the outflow is concentrated into thin cylindrical streams having a very small. radiation heat loss, the liquidity of the slag is maintained. This was not achieved by the previous arrangements of the outflow opening where the outflow of the slag was effected in thin layer over the entire area of the circumference of the opening and in case of low loads and low temperature was subject to freezing and formation of stalagmites which endangered the slag granulation and transport means arranged underneath the outflow opening.

Also in case of a sudden increase of load the arrangement of the outflow opening according to the invention presents important advantages. In case of such a sudden change, the temperature in the combustion chamber is increased rapidly and the slag collected and solidified on the walls of the chamber melts away, falls in pieces on the floor of the chamber and is taken away by the liquid slag through the outflow opening. The slag granulation and transport means are heavily overloaded by the enormous quantity of slag, which can be characterized by the name of slag-floods, and must therefore be correspondingly dimensioned. In the arrangement according to this invention, the dam disposed at the circumference of the outflow opening prevents the rapid outflow of the pieces of solidified slag, thus preventing also the overloading of the granulation and transport means. The level of the slag bath l5 on the floor l of the chamber rises slightly and the outflow streams 1, 8 will become more voluminous, but the rapid outflow of slag is rendered impossible by the dam. The solid pieces of slag are kept in the slag bath l5, until they are molten properly.

By the arrangement of the nozzles 5, 6 it is intended to keep the streams 1, 8 of the slag away from the wall I2 of the outflow opening 2. The streams l, 8 are separated from the wall 12 by a, distance a: (Fig. 3) and they are brought closer to the centre of the outflow opening. The nozzles 5, 6 also shield partly the slag granulation device, arranged underneath the outflow opening, from the radiant heat transferred from the combustion chamber.

The nozzles 5, 6 may be disposed either in the centre of the longer sides of the opening, as shown in Fig. 2, or alternatively, at the sides of minor axis of the ellipse. This case is indicated in Fig. 4', where also the inlet and outlet of the cooling fluid from the tubes 3, 4 are shown diagrammatically by arrows.

What I claim is:

1. In a furnace of the character described, av

combustion chamber having walls and floor of heat resisting material, the floor of said chamber having an opening for the outflow of liquid slag, a dam obstructing the greater part of the circumference of said opening and restricting the outflow of slag to one or more desired points, and

nozzles shaped at said points of the circumference to assist the outflow of the slag.

2. In a furnace of the character described, a combustion chamber having walls and floor of heat resisting material, the floor of said chamber having an opening for the outflow of liquid slag, a dam obstructing the greater part of the circumference of said opening and restricting the outflow of slag to one or more desired points, and

nozzles shaped at said points of the circumference to assist the outflow of slag, said dam and said nozzles being formed by fluid cooled tube means, bent to the required shape.

3. In a furnace of the character described, a

combustion chamber having walls and floor of heat resisting material, the floor of said chamber having an opening for the outflow of liquid slag, a dam obstructing the greater part of the circumference of said opening and restricting the outflow of slag to one or more desired points, and nozzles shaped at said points of the circumference to assist the outflow of slag, said dam and said nozzles being formed by fluid cooled tube means, a row of studs or fins welded to said tubes to increase the height of the dam and to give proper shape to the nozzles.

4. In a furnace of the character described, a combustion chamber having walls and floor of heat resisting material, the floor of said chamber having an opening for the outflow of liquid slag, a dam obstructing the greater part of the circumference of said opening and restricting the outflow of slag to one or more desired points, and nozzles shaped at said points of the circumference to assist the outflow of slag, said nozzles being disposed one opposite to the other on the circumference of the opening.

5. In a furnace of the character described, a combustion chamber having walls and floor of heat resisting material, the floor of said chamber having an opening for the outflow of liquid slag, a dam obstructing the greater part of the circumference of said opening and restricting the outflow of slag to one or more desired points, and nozzles shaped at said points of the circumference to assist the outflow of slag, said nozzles being disposed so as to separate the streams of outflowing slag from the wall of the opening and to bring themcloser to the centre of the open- JOSEF CERMAK. 

